Cooling tower



Aug. 26, 1952' T. s. PARK, sR., ET AL 2,608,398

' COOLINGzTOWER Filed Oct. 18, 1948 4 Sheets-Sheet 2 INVENTORS. V Tkncy 5. PAR/(,SR. 4

BY 7%: Pug, Jr.

.4 r TORNE y.

Aug. 26, 1952 1 T. s. PARK, sR., ET AL 2,608,398

COOLING TOWER Filed Oct. 18. 1948 4 Sheets-Sheet s IIH T g fl r TORNE Patented Aug. 26, 1952 UNITED" STATES PATENTOFFI'CE Tracy S. Park, Sr., and Tracy S. Park, Jr.,

Houston, Tex.

Application October 18, 1948, Serial No. 55,206

Mechanical draft towers for cooling waters are generally well known but they have serious limitations. Generally they depend upon the formation of droplets, in a rain of Water, which are cooled by evaporation by passing through 2. current of air countercurrent to the rain of droplets.

These towers have the serious limitation that although they are highly efiicient in cooling the surface ofthe droplet by evaporation therefrom, the interior of the droplet must be cooled by conduction. The initial step of the cooling by surface evaporation of the droplets is usually rapid, but the sub-sequent cooling by conduction through the dropletis relatively slow, so that towers of great height must be constructed to give the time of contact which is necessary for the second stage cooling eifec ta An effortis made to out down this time in such towers by interposing baffling means during the course of the descending droplets so that the drops may be intercepted and reformed in order to cut down the time required for the second stage of the coolingoperation This, while giving some improvement, cuts down the tower dimensions but moderately.

In order to assist in the process of the breaking up of the droplets, the baifiesare spaced apart in a vertical direction sufficiently to impart a free fall velocity to the droplet sothat the contained kinetic energy will cause the droplet to; Splatter and break up. This feature adds to the vertical height of the column. Alimitation of this type of tower is that, except as the water droplets are delayed by the baflies, :the droplets are in free fall through an upwardmoving current of air and therefore the retentiontime in the tower for a given air velocity (air to water ratio) is deter mined by the laws of gravity. The solution reached by prior art cooling tower constructions is to make the tower tall enough to give the required retention time forand kinetic energy to the water droplets at the rated water and air throughputs.

Another difiiculty resides from the fact that it is not possible in this type of tower to obtain droplets of uniform size. The droplets are of sizes governed by a statisticallaw. Thus,yde pending upon the circumstances, someof the drops are large and some small. Thus, they are unequally cooled, the large drops being cooled relatively less than the small drops. If the drops are made small enough to get better cooling, then they are carried out in the air stream and the water loss becomes excessive. 3

We have found that we may increase the efiiciency of the heat interchange in the second 11 Claims. (Cl. 261-411) stage by causing the partially cooled droplets to pass through the towers, not in free fall, but in retarded flow. We accomplish this object by causing the droplets to condense into substantially vertical thin films of water which fioW down vertical partitions as moving sheets of water under the influence of adhesive and viscous forces. We thus form sheets of suificiently small thickness to flow as unbroken filmsunder said adhesive and viscous forces to expose the water in a surface such that the ratio of the surface to the thickness of the film is extremely large, the films ranging in size up to about .035'f and up to, for example, 20' in height and 12' in Width.

The rate of movement of an elementary particle of the sheet of water is slower than the rate of free fall of droplets. This permits of equilibrium to be established in a smaller vertical height than in the case of conventional spray type cooling towers previously referred to. By extending the water in thin sheets, equilibrium between the water and the air may be established and the water cooled to a substantially uniform temperature. .The material reduction in vertical tower height which we thus obtain is reflected in a material saving in power resulting from the reduction in pumping head of the water necessary to lift the water to be cooled to the top of the tower. It also minimizes the cost of construction of the tower. 7 We have also found it desirable to limit the total air velocity through the spray pre-cooling section to an amount insuificient to carry over any material amount of water as water spray.

We have found that we may obtain such advantageous result by segregating the air stream required for the spray pro-cooling section and for the film cooling section. In this manner we limit the air stream in the pro-cooling section to prevent spray carry-over and also provide the required additional air for the film cooling section. We have also discovered that it is advantageous to employ in the film-cooling step a cross-flow of air and water, i. e., to pass the water in a downward direction and the air in a generally cross-wise direction substantially perpendicular to the flow of water.

This procedure has the advantage that the spray section may be superimposed upon the film section and the water passed through from the spray section directly to the film section.

We divide the input air into separate air streams from a single plenum so that substantially fresh air passes countercurrent through the spray section and substantially fresh air through the film chamber. This permits of the maximum cooling by the relatively small volume of air passed through the spray chamber, since the air is at substantially the wet bulb temperature of the input air and also a maximum cooling in the film section, since the partially cooled water is contacted with the same input air. The air in the cross flow is contacted with Water of higher temperature as it travels across the sheet and thus the vapor pressure-partial pressure differential between the water and moist air is kept relatively high.

We have also found that we may substantially prevent water entrainment in the high air velocity film section by employing the following expedients. I

The water descending in droplets from the spray section is coalesced in a substantially horizontal film section in a thin sheet. The horizontal film section has horizontal slots. Extending vertically from the horizontal film section are vertical partitions stackedin close proximity to each other. The horizontal length of the slots embrace is substantially equal to the width of the vertical film partitions. The shape of the slot and topo-f the partition is such as to present a Venturi throat at the slot. The water which coalesces on the horizontal film partition is caused to flow in a thin film over the edge of the slot and downward over the surface of the partition. Because the slot embraces the full width of the partition, the sheet covers the entire width of the partition from the entry to the bottom of the partition.

The air is introduced from a plenum chamber at one end of the partition and passes between the partitions across the descending films and exits at the other end of the partitions. A portion of the air near the top of the partition exits through the slots. Because of the Venturi shape of the slots, the velocity of the by-passed air through the slots is high. Water which tends to cascade into the slots, or otherwise enters the slots in the form of drops, is carried upward by the high velocity air stream in the slot and is not permitted to enter the film section. The air jetted through the slot enters the enlarged spray section wherein the velocity of the air drops materially. Any entrained droplets of water drop out. The air velocity is also insufficient to 'lift any substantial portion of the water entering the spray section.

We may also, by proper positioning of the spray nozzles, impart a direction of fall of the spray droplets at an angle to the plane of the film partitions, thus also preventing the passage of the droplets in vertical free flow through slots and between the partitions.

Provision is also made to insure that the water film is unbroken and flows quietly down the sheet. This is aided by isolating'the filming panels from vibration. To assist in this purpose the forced draft fan is mounted independently of the film partitions, and the tower and the partitions are supported on a foundation independently of the fan and tower housing. The partitions are then isolated from vibratory forces. By limiting the thickness of the water film we also aid in producing a uniform unbroken film of water on the partitions.

In order to embody these objectives we have designed a water cooling tower ofnovel design. A preferred embodiment will be hereinafter described in conjunction with the drawing, in which Fig. 1 is avertical section through one form of our cooling tower;

Fig. 2 is a plan view of Fig. 1 with parts removed and parts shown fragmentary for clarity;

Fig. 3 is an end view of Figs. 1 and 2;

Fig. 4 is a section taken on line 4- of Fig. 1;

Fig. 5 is a perspective of one vertical film unit;

Fig. 6 is an enlarged detail of the end of the film unit;

Fig. 7 is a fragmentary section taken on line 'i--'! of Fig. 5.

The cooling tower is erected upon a foundation I. Erected upon said foundation are vertical columns 3 and top stringers 3' upon which is mounted the sheeting to form the front face 2. Mounted in the face 2 is a circular guard ring 4 in the center of which is mounted a propeller fan 5 actuated by a source of motive power 1. A screen 6 is mounted upon ring 4 as a guard for the fan 5. The fan and power unit are mounted upon support 8 which is positioned upon foundation I. The fan and motive power are thus inde pendently mounted of the structure, so that the vibrations of the fan are not transmitted to the structure.

The cooling tower, as illustrated in the preferred embodiment shown in the drawings, is composed of two cooling sections between which is positioned the discharge section 30'. Each of the cooling sections has a rectangular cross section and is formed 'as follows: The side walls I2 (see Figs. 2, 3, and 4) are formed of sheeting supported upon vertical columns mounted on the foundation. A plenum II which takes the discharge from the fan 5 is formed by the side wall 12, a top 9, and the foundation I, coacting with the face 2 of the plenum chamber. The discharge from the'plenum l I is formed by the Walls l2 and beams l0 and vertical columns iii. Mounted at I the discharge from the plenum chamber II is a vertical partition or splash wall i5 which extends above the top 9 of the plenum chamber and which, coactingwith the splash plate 16 and the'incl'ined stack side. 3| (to be described later) forms a spray chamber IS in which is mounted spray nozzles l8 mounted upon a spray pipe I!- connec'ted to hot water input line 19. The top of the spray chamber may be open to the air or covered and suitably vented as preferred.

It will be observed that the plenum chamber H is substantially of rectangular cross section. Beneath the spray chamber is a film chamber 2% of substantially rectangular cross section and of width equal to the width of the plenum chamber I l and of height substantially equal to the height of the plenum chamber H V Positioned in chamber 20 is a film section composed of a plurality of stacked vertical plates constructed in h the following manner. They are formed in aplurality of sections each composed ofqsheets 2| of length substantially equal to the height of the film section and of a width substantially equal to the depth of the film section. They are connected by rods 28 and'nuts 3i! and spacer sleeves 29. The top of the vertical partitions 2! carry heads 22 having a wedge section 21 and a box section 124 into which is fitted the top of the partition 2| from which the wedge section depends. The wedge section 2'! fairs to a line where it intersects the surface of the partition 21. The section 22 has a vertical face 25 and a horizontal top 25. The top 26 of each of the partitions is coplanar.

It will be observed that the distance between contiguous faces "of the partitions 2| is greater .aeoaaes of the heads 22. The space 25 between the faces 25 thus forms a slot extending the full width of the partition and each partition is positioned between two adjacent slots and'each slot feeds the opposing faces of adjacent film partition 2|. The wedge sections 21 form a Venturi opening into the slot between the faces 25 with the throat at 25, i. e., at the entrance to the slot. Thus, for the purpose of illustrating the nature of the separation, and not as a limitation thereof, the following dimensions may be taken for such illustrative purpose. The separation between the faces 25 may be while the panels 2| may be of sheet material, such as plywood, asbestos, cement boards, etc., giving a face-to-face separation between the contiguous faces of 2| of 11%;. The width of each of the head sections 26 between the faces 25 of each box section is equal to about 1". It will thusbe seen that the solid top surface 26 of each box section is approximately three times the slot opening 25 and that the space between the partitions is more than three times as wide as the slot 25'. While these dimensions may be varied somewhat, it is desired that the slots extend over the entire width of the panel and be less in area than the horizontal film partitions 26 and substantially smaller and preferably less than of the distance between the partitions 2|.

A multiplicity of these panel unit are stacked in sections across the width of the chamber 20 from one wall to the opposite wall l2 in the above spacing and stand upon foundation I. These are otherwise disconnected from the cooling tower structure so that any vibration of the structure is not imparted to these panels. It will also be noted that the fan and its motive power are separately positioned from the foundation and are not connected to the tower structure or the partitions. The partitions are thus vibrationally isolated from the fan and tower structure. The spray headers l1 and the spray nozzle l8 are positioned in spaced relation across the width of the film chamber and spray chamber so that the spray which is generated falls uniformly across the entire area of the spray chamber into the film chamber beneath the spray chamber. The distribution of the nozzles and the coplanar position of the tops of the horizontal film surfaces 26 result in a uniform distribution of water over the slots. Because of the rectangular cross section of the plenum chamber H and the film chamber and the rectangular section of the tunnel formed between the vertical partitions, and since the fan diameter is less than the distance between walls I2, we have positioned a deflector 6 plenum chamber entersin between the partitions 2| to discharge through rtheyopening 21 of the chamber 2|), which opening 21' is of the same nature as the discharge from the plenum chamber I in other words, it is of the same cross section. The partitions 2| are thus substantially I 4 in the form of a vertical plate with a quadrantcross section mounted near the tips of the fan blades upon the frame-work l3. The air stream from the blade of the fan 5 is directed on both sides of the quadrant section to produce a uniform static pressure in the plenum chamber across the width and length thereof. It will be observed that the fan diameter is substantially equal to the height of the plenum chamber so that with the deflection and this proportioning we get a uniform pressure distribution across the width and length and height of the plenum chamber.

The partitions are placed edge-on to the plenum chamber, i. e., so that the surfaces of the partitions are parallel to the axis of the opening from the plenum chamber and preferably parallel to the axis of the fan. The air from the embraced by the discharge from the plenum chamber and by discharge 21'. The air from the plenum chamber thus passes over substantially all vertical surfaces of the partitions 2| and discharges in substantially parallel sheets through the opening 21'. A major portion of the air, flows in a direction generally perpendicular to the mo tion of the film and generally parallel to the plane of the horizontal surfaces 25. i

A portion of the air near the top of the partitions is discharged upwardly through the slots 25 to enter into the spray chamber to pass through the spray and to be discharged'through thetop of the spray chamber. It will be observed that the fraction of the air which is discharged through these slots is but a small fraction, about 5% to about 15%, of the total air which is introduced from the plenum chamber. This is obtained by the proper proportioning of the height and width of the platesand the size of the slots as described above. It will also be observed that the air passing through the spray chamber is of much lower velocity than the air passing between the plates and that the air passing through the slots 25' is of higher velocitythan inthe spray chamber. a i 4 The hot water enters through .the conduit 5"! through the sprays IS in the spray chamber l9 where it meets the air stream which is discharged through the slots, and thepartially cooled droplets deposit upon the coplanartops 2B of the film partition where they are coalesced and form a horizontal film over all the surfaces 26 which then spreads over the edge of the slots and descends to the opposite vertical faces 25 of the heads 22. Any water which cascades in the form of drops or sheets into the slot opening 25 is car ried out of the slot by, means of the air passing at high velocity between the slots. The water which passes downward is in the form of a film which runs over the vertical faces 25; the sloping faces 21 and the verticalsheet down both sides of the panel 2|. Thevertical'faces permit of the establishment of the film before it passes to the rearwardly sloping faces 21 which establish an obtuse dihedral angle with the vertical face of the partitions. This assists in assuring that the film will flow onto the vertical partition faces in uninterrupted smooth flow and. also minimizes cascading. It will also be observed that the slots are the full length of the panels and the sheet of water covers the entire width of the panels.

We may also direct the spray at an angle to the plane of the film partitions 2| and to the plane of the top surface 26 of the heads 22 in order to aid in preventing free entrance of droplets into the space between the partitions 2|. Thismay be accomplished by directing the spray at such an angle, by proper design of the spray heads, as will be well understood by'those skilled in this art. i

. The rate of input of the water is controlled so that a sheet is established, for'example, of thickness of between about .01 to about .035". We obtain a sheet of water which is unbroken and continuous and adheres to the surface of the film partition to flow under this adhesion tension and flow down the vertical face of the panel;

The water descends over theopposite faces of the :film .partitions *2 l and over I the entire surfa'cethereof exposed to the air :streamand drops serve the 'integrity of the film and'p'rev'entany V cascading or shaking off of the film from the face of thejvertical'panel. The water drops off the end of the vertical panel and collects in chambers 26 from which it is removed by suitable pumping-means not shown.

Themoisture laden air discharged from between the panels 2! exits through the opening 2'1 intothe chamber 39 formed as follows: Positioned upon foundation I and between the side wall sheathing I2 is a plurality of vertical columns 34 extending-in two rows across the width of the foundation. Intermediate taller columns 33 are likewise positioned. Mounted upon these columnsand on beams 37 are she'athings 38 and as.

,The sheathing 36 forms a dihedral angle whose apex is positioned on the column 33 on which also rests the beams 32. The sheathing 38 extends from the lower edge of the air discharge opening 27' and is connected to the sheathing 3-6 and is positioned atan angle'to the horizontal more acutely than that of sheathing 3t. Sheathings 38 and 36 form an upwardly slopin solid partition of varying degrees of inclination which diroot the air exiting from 21 into chamber 38 upwardly into chambered. Positioned between the chambers 30and 30 are a plurality of angularly positioned beams 32 spaced across the width of the chamber 30' and positioned upon a beam carried by the vertical columns 33.

In the space between said beams 32 are'inclined bafiles 320 which are positioned at an angle to the vertical and extend from one wall [2 to the opposite wall I2. At the top of the chamber 353' are inclined plates 3! extending between the side walls I2 Which slope outwardly to give a Venturi throat 3 l at the top of the chamber 39. The air exiting from 2'? enters chamber 35 and is dil ected into the chamber 30 by means of the sloping bottoms 36 and 38 and into the chambe 3%? by the directing baflles 32a. 7

It will be observed that the structure shown in Fig. 1 is symmetrical around the center line, passing through the center of the chamber 3 showing two spray and filming sections, one on each side of the discharge sections 3i and BI. It is, of course, possible to vary this construction to have only one spray and filmin section with a suitable discharge of the exiting air from 21 through a single stack or through louvers positioned in 21', as desired, to atmosphere or to a stack.

It is advantageous to employ a discharge stack, such as illustrated in Fig. 1, to carry the discharge air in a direction upwardly and to discharge the .air at a point above the spray sec tion, as illustrated in Fig. l, to prevent the recirculation of moist air icy means of any accidental down-drafts.

The above construction employs one central discharge stack between two opposing film sections. In this construction two mutually opposing air streams enter this section. Means are provided to separate and deflect these streams so as to merge them into a high velocity stream of air exiting in a vertical direction from the stack. By means of the devices employed in our stack structure, this merging of the opposin air streams is accomplished with minimum turbulence and thus with minimum retardation in the velocity of the air streams or development of material back pressure. By imparting a relatively high velocity to this exiting stream the air of high relative humidity is carried into the atmosphere to a point remote from the fan suction.

The air streams enter from the opposed film chamber outlets 21'. The air passing through the film chamber between the film partitions 2 I moves in parallel separate sheets and enters with minimum turbulence into the chamber 3d. The air in the upper portion of the chamber is deflected by thebaiiies 352a which extend across the opening 27 and slice thevertical airsheets exiting from between the'film partitions 2! into a plurality of longitudinally extending air stream strips and then direct them at a gentle angle into the chamber 30. The air in the lower section of chamber 30 strikes sheathing 38 which is mounted at a small angle to the horizontal, and sheathing 36, which is mounted at a greater angle to'the horizontal than is sheathing 38, causes the air to change direction gradually and ice directed between the bafiles 32a to pass as described above into the chamber as.

The velocity of the air passing through the slots between the baflies32a and at the entrance into chamber 30 is increased due to the restriction in area and the velocity in chamber 3! will be higher due to the merging of the streams in this chamber. 7 a

, It willbe observed that except within the fan ring 4 the air in the stack area is at the highest velocity and lowest pressure, causing the air to exit from the stack structure upwardly with sufficient velocity to prevent recirculation to the input fans. Additionally, the air after leaving the film chamber and entering the high velocity stack section is not in contact with the water, the water being separated from theair and collecting in basins 2G :beneath the film partitions.

It will be observed that in this construction the air from the plenum chamber ii is divided into two independent streams, one at 'a low 'velocity air stream passing through the spray chamher and discharging independently of the remaining. air stream. The remaining air stream is passed at a relatively high velocity over a vertically descending relatively 'quiescent film of water flowing under adhesion tension. By isolating this film from the rest of the structure and thus maintaining it substantially vibration free, we have obtained this material aid in maintaining the integrity'of the film. It will also be observed that the film is formed in such manner that there is substantially no water descending between the "vertical filming panels in spray form. This is accomplished, as has been shown, by the high velocity lay-passed air which is passed through the head sections of the panels to remove any spray which may descend between the panel sections. This is obtained by providing slots of openings smaller than the spacing between the panels and extending the full length of the panels whereby the water is filmed over the entire surface to produce a quiescent thin film which covers the'entire surface of the filming panel. This insures a maximum utilization of the filming surface.

While we have described a particular embodiment of our invention for the purpose of illustra- 1 9 tion, it should be understood thatvarious modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

We claim:

1. A mechanical draft water cooling structure, comprising a film section, a plurality of vertical partitions in said film sections, spaced from each other, the upper end of each partition having a wall section converging toward the complementary wall section of the adjoining partition to form longitudinally extending passageways for passage of air and water extending over, the width of said partitions at the top. of said partitions and positioned between adjacent partitions, an air inlet plenum connected to said film section at one side edge of said partitions; an air outlet to said film section at the other s'ideledge of said partitions, a spray chamber positioned on top of said film section above said passageways and connected to the spaces between the partitions, spray nozzles in said spray chamber positioned above said passageways, and an air discharge from said spray chamber. 7 i

2. A mechanical draft water cooling structure, comprising a film section, a plurality of vertical partitions spaced from each otherin said film section, the top end of said partitions having coplanar horizontal surfaces, the upper end of said partitions adjoining said horizontal surfaces at the top thereof being wedge-shaped, and the opposite faces of the partitions at said upper wedge-shaped end converging downwardly, adjoining partitions at said wedge-shaped sections forming Venturi passageways between said horizontal surfaces extending longitudinally over the width of said partitions, the throat of said Venturi passageway being adjacent the top end of said partitions, a water inlet positioned over said coplanar horizontal surfaces, means for distributing the water over all of said horizontal surfaces and over the length of said passageways, means for passing air between said partitions in a direction parallel to said horizontal surfaces, and means for discharging a portion of said air between said film partitions and through said pas sageways.

3. A mechanical draft water cooling structure, comprising a film section, a pluralityof vertical partitions spaced fromeachother, each of said partitions carrying a headsection extending over the width of said partitions, said head section having a box section and a wedge section, positioned at the top of said partitions, the top surfaces of said box sections being horizontal and the said tops of said head sections of said partitions bein coplanarand the box sections of said head of adjacent partitions being spaced from each other to form a slot whose width is less than the spacing between adjacent partitions, said adjacent wedge sections forming a Venturi opening from said slots to the space between adjacent partitions, means for distributing water over the said horizontal top surfacesand means for passing air between said partitions in a direction substantially parallel to said horizontal top surfaces.

4. A mechanical draft water cooling structure, comp-rising a film section, a plurality of vertical partitions spaced from each other, each of said partitions carrying a head section extendingover the width of said partitions, said head section having a box section and a wedge section, positioned at the top of said partitions, the top surface of said box sections being horizontal and the said tops of saidhead -sections of said partitions other to form a slot whose width is less than the spacing between adjacent partitions, said wedge sections forming a Venturi opening from said slots to the space between adjacent partitions,

means for distributing water over the said horizontal top surfaces, means for passing air between said partitions in a direction substantially parallel to said horizontal top surfaces, and means for by-passing a portion of said air between said'slots.

5. A mechanical draft water cooling structure, comprising a film section, a plurality of vertical partitions spaced from each other, each of said partitions carrying a head section extending over the width of said partitions, said head section having a box section and a wedge section positioned at the top of said partitions, the top surfaces of said box sections being horizontal and the said tops of said head sections of said-partitions being coplanar and the box sections of said head of adjacent partitions being spaced from each other to form a slot whose width is less than the spacing between adjacent partitions, said wedge sections of adjacent partitions forming a Venturi opening from said slots to the space between adjacent partitions, a spray section positioned over said slots, spray nozzles in said spray section, and means for passing air between said partitions in a direction substantially parallel to said horizontal top surfaces and through said spray section. j i t 6. A mechanical draft water cooling structure, comprising a film chamber, a plenum chamber at one side of said film chamber, a discharge opening from said plenum to said film chamber, means for generating air pressure in said plenum chamber, an air, discharge opening from the opposite side of said fihn chamber, a pluralityof vertical partitions spaced from each other, said air discharge opening substantially embracing the edges of the partitions, the upper end of each partition having a wall section converging toward the complementary wall section of the adjoining partition to form Venturi passageways extending over thewidth of said partitions at the top thereof and between adjacent partitions, a spray chamber positioned over said film chamber; spray nozzles in said spray chamber positioned over said slots, and an air discharge from said spray chamber.

'7. A mechanical draft cooling structure, comprising a film chamber, a plenum at one side of said film chamber, a discharge opening from said plenum tosaid film chamber, meansfor generating pressure in said plenum an air discharge opening from the opposite side of said film chamber, a plurality of vertical partitions spaced from each other, saidair discharge opening from saidplenum substantially embracing the edges of said partitions, each of said partitions carrying a head section extending over the Width of said partitions, said head section having a box section and a wedge section, positioned at the top of said partitions, the top surfaces of said box sections being horizontal and the said tops of said heads of saidpartitions being coplanar, the box sections of adjacent partitions of said head sections being spaced'from each other to form aslot whose width is less thanthe spacing between adjacent partitions, said wedge sections forming a Venturi opening from said slots to the space between adjacent partitions, a spraychamber positioned over ,said film chamber, spray nozzles positioned in said :spray chamber over said slots, and an-air discharge from said spray chamber.

8. A mechanical draft water cooling structure, comprising a central {air discharge stack, opposed air inletsinto said stacks, upwardly inclined baillesoonnectedto the lower edge of each of the air inlets, opposed baffles being connected to each other I. at a dihedral angle whose apex is at approximately the center line of saidstaclr, a plurality of angular baffles positioned in said central stack above said inclined bafiles and ex tending across the said openings and spaced from each other, an air discharge chamber in said stack above said angular baffles, a film section connected -to each of said air inlets, a plucollecting chamberunderneath said partitions.

9. A mechanical-draft water cooling structure,

comprising a central air discharge stack, opposed air inlets into said stacks, upwardly inclined baffles connected to the lower edge of each of the air inlets, said baffles being connected to each other at a dihedral angle whose apex is at approximately the center line of said stack, a plurality of angular baflles positioned in said central stack above said inclined baffles and extending across the said openings and spaced from each other," an air discharge chamber in said stack abovesaid angular baffles, a film section connected to each of said air inlets, a plurality of vertical partitions'in each of said film sections spaced from each other, the top end of said partitionshavingcoplanar horizontal surfaces, the upper'end of said partitions adjoining said horizontal surfaces atthe top thereof being wedgeshaped, and the opposite faces of the partitions at said upper wedge-shaped end converging downwardly, adjoining partitionsat said wedgeshap-ed sections forming air and water passageways between said horizontal surfaces positioned over the spaces between said partitions and extending longitudinally over the width of said partitions, a water inlet positioned over said coplanar horizontal surfaces,'means'for distributing the water over all of said horizontal surfaces and over the length of said passageways, an air inlet plenum connected to said film section, a spray chamber positioned on top of said film section and over said air and water passageways, spray nozzles in said spray chamber positioned above said slots, an air discharge from said spray chamber, and a water collecting chamber underneath said par- 7 titions.

10. A mechanical draft water cooling structure, comprising a central "air discharge stack, opposed air inlets into said stack, upwardly inclined bafiles connected to the lower edge of each of the air inlets, said baflies being connected to each other'at a dihedral angle whose apex is at approximately the center line of said stack, a plurality of angular baffles positioned in said central stack above said inclined baffles and extending across the said openings and spaced from 'each other, an airy discharge cham er in iaeoaees 12 said stack abovesaidangular bafiies,;a.fi1m,sec tion connected to 'ea'ch of said air inlets, a plu-' rality of verticalpartitions in each of said :film sections spaced from each other, the'top end of said partitions having coplanar horizontal sur faces, the upper end of saidipartitions adjoining said horizontal surfaces 'at the .top thereof be-' ing wedge-shaped, and the opposite facesof the partitions at said upper wedge-"shaped end con.- vergingdownwardly, adjoining partitions "at said wedge-shaped sections forming Venturi-passageways between said h'orizontal suriacespositioned over the spaces between: saidpartitions and ex,- tending longitudinally over the, width of said partitions, said passageways having the throat of said venturi at the entrance to said :passageways, a waterinletzpositioned over saidicoplanar horizontal surfaces, meansfor' distributing the water over all of said,hor,izontal surfaces, an air inlet plenum connected tosa-id film section, a spray,chamber;positione.d on top pr said film section, spray nozzlesinsaidspray chamber-positioned above said passa cwaysan air discharge from said spray chamber,andawater'collecting chamber underneath said partitions; u .11. A mechanical draftwatercoolingstructure, comprising a central air discharge stack, opposed air inlets into said stacks; upwar n ned barfies connected QtQgthQ lower edge of each of the air inlets, saidbafliesbeingconnected to each other at a dihedral angle whole apex is at'approximately thenenterlineof said stack, a plurality of an ular baffies positioned in said central stack above, saidinclined bafiies and extending across the said openings andspaced from each other, an air'discharge chamber in said stack above said angular ,baffies, a film section connected to each ofsai d air inlets, aplurality Of vertical partitions in each of said film sections spaced. from each, ot er, ca he s id p ti i carrying a head section extending over, the width of ,saidpartitions, said head section having a 'box sectionand a wedge section, positioned at the top or said partitions, the top surfaces of said box sections being horizontal and the said tops of said head sections of said partitions being'coplanar and the box sections of said head ofadiacent partitions being spaced from, each other to form a slot whose width is less than thespacing between adjacentpartitions, -;an air inlet plenum connected to said film,section,;a spray chamber positioned on top of jsaid film s ection,1 spray nozzles insaid spray chamber positioned above card slots, an air; discharge iromsaid spray chamher, and a water collecting chamber underneath said partitions. v V

' "TRACYSPLARK, SR.

4 "I'RACY'SLPARK, JR.

narnrtsnons-orrnn The following ..,r,efe'rences are-of record in the file of this patent:

UNITED TATES PATENTS 

